| 摘要 |
PURPOSE:To enable a printing pressure to be kept at constant level regardless of a change in a power supply voltage by constituting the title device in such a manner that the setting time of a timer may meet a change in the power supply voltage, i.e. the short time when the voltage is high and the long time when the voltage is low. CONSTITUTION:In a circuit of a driving part, a drive coil S1, transistors Tr1, Tr2, diodes D4, D5 and a Zener diode ZD1 are configured in the same way as the previous model. In addition, on a timer means connected to a point P7, open collector-type buffers B2-B4, a resistor R1 whose one end is connected to a drive power supply, a capacitor C1, pull-up resistors R4, R5 and a comparator CM1 to which Vref is input as a reference voltage are provided. Under the above configuration, the timer means works to set time in accordance with a change in a power supply voltage; i.e. a short time when the voltage is high and a long time when the voltage is low. Consequently, a printing pressure can be kept at constant level and a high printing quality can be obtained. |
